Wow... there are a whole lot of responses to wade through... FWIW, I have found that drum tuning and mic positioning seem to have even more influence on the end result than mic or pre selection, but that's not to say that mic and pre selection is totally unimportant [because they are, just not quite as critical in my work as placement].
I have never gotten a bottom snare mic to work for me worth a damn. Even after spending hours tuning and retuning the bottom snare head, trying all kinds of different snare strainers, from 20's to 14's to some of the weird spaced specialty strainers... the "undersnare" mic always sounds "broken" to me. Obviously, some folks seem to use it with great results, but I have found that with a good snare drum, good snare drum tuning, and careful microphone positioning that a bottom snare mic is absolutely unnecessary to get the "crack" you're trying to achieve.
Tuning is tuning, head selection is no minor part of tuning, and every kind of head sounds different. I certainly have some favorites for top snare heads, like the good ol' Remo "Ambassador", but I've seen brothers use all kinds of stuff with mixed results. The Remo "Ambassador" is kind of a standard and is more often than not the 'safe' bet. The Remo 'Power Stroke' head seems to be popping up a lot with a bunch of drummers, but I have kind of mixed feelings about them... I think they kinda lack a lot of the overtones I like to hear from a well tuned snare drum. While we're here... for 98% of the 'rawk' stuff I work on, tuning the snare drum to a "D" will usually give you results to die for.
For the most "crack" I have found you can get from a snare drum a Remo "diplomat" head on the bottom of the drum with a "14" strainer is usually the ticket. A "12" strainer works even better, but you usually have to order those many weeks in advance and they're not inexpensive. It seems that during the 80's hair metal crisis the "20" strainer became the standard... I find them a bit overly washy in terms of the after sizzle, but again, that could just be me.
On mic positioning... whew... options, options, options... I usually start with a mic 4-8" off the side of the drum, preferably with the H/H in the null of a Cardioid, Hyper Cardioid or Figure 8 pattern mic... with that mic aimed at the shell of the drum [between the top and bottom rim]. Often, a Shure 57 works like a charm in this position, but sometimes it sucks... depends on the drum and the tuning, the day, the atmospheric pressure and what I had for breakfast.
The Beyer M-201 is often a great alternative to the 57, a Groove Tubes GT-44 with the cardioid capsule will sometimes work like a charm,
A Shure SM-81 can be absolute magic on some occasions, Josephson's work, even the occasion cheap Chinese lg. diaphragm condenser will work. I have even attained excellent results with
an AKG C-414 [even the ULS and TL ones... the ones that pretty much suck for almost every other application], as well as a TLM-103 and a whole bunch of others... experiment, experiment, experiment.
There are times when the side of the drum positioning doesn't work as well as I'd like, at those times I will go to the more traditional "mic on the head of the drum where no ear would ever dare to go" mic'ing technique. First let me mention that there are two parts that are critical for you to pay attention to when you're mic'ing a drum in this manner. The center of the drum and the spot that I call "ground zero", which is where the drummer actually hits the snare drum when playing. With a right handed drummer is usually an inch or two northwest of the center of the drum.
For this kind of a thing I like to use two mics. The first is usually a dynamic, like a 57 or M-201, the second a small diaphragm FET condenser like an SM-81 or AKG 451 [with a 10 or 20 db pad on it]... though recently I have used things like the Joesphson C-42 in that application with stellar results. With the dynamic mic, what you're pretty much looking for is the "size/note" of the drum, the condenser mic is there to get you the "whack" and "snares" you're looking for [without sounding broken].
I usually have the dynamic mic come in like 1/8th to 1/4 inch over the rim, pretty much horizontal to the floor, and aimed at the center of the drum [most snare drums are angled, so sometimes you have to angle the head of the mic down a couple of degrees relative to the part of the mic with the connector, or move the mic to the other side of the H/H stand (which brings it in at a different angle, and is generally lower than where you usually snake a snare mic in... ya know, the "tom side" of the H/H stand) to get it to aim at the center of the drum properly... don't be afraid to experiment with very slight angle changes as they can make a huge difference!!].
The second mic, the small diaphragm condenser mic comes in at like a 30 degree angle relative to the first mic, their grills touching in the front with the condenser mic directly over the dynmic mic, aimed at "ground zero" will usually net you "crack" for days. Sometimes a little EQ on this mic is a help though I generally try to avoid any EQ, it's not always possible. Scallop a little mids from this [find the note of the drum and bring it down a bit allowing the dynamic mic to grab this part of the sound... they usually handle it better than the condenser... usually the 400-1kHz range, +/- like a 1/4 octave], maybe add a smidgeon of upper mids, ya know like that 4-6k range, relatively small bandwidth, like a third of an octave or a tad less... not much, maybe a db or two, just a tad to bring the snares a bit more forward.
All of this, no matter what mic you use, will not work worth a damn if the drummer sucks. Usually, a good drummer won't be behind bad sounding drums. I don't know if it's the way they hit the drums or they just have a tendency to gravitate towards drums that don't suck... but I have found in my travels that more often than not, all drum sound problems can be traced directly back to the operator of the drum kit... though I have tuned more than one "famous" dude's drum kit.
...and finally... we get to the "don't put great mics on drums because they might get hit" thing. If you're working with a drummer that is inaccurate with their attack that they could potentially hit a mic... there isn't a damn thing you can do about the drum sound. It is undoubtedly going to suck ass. Where the drummer hits the drum is a major,
major,
major contributor to the sound of the drum. If the drummer isn't seriously consistent, there ain't jack shit you can do to save the sound except blow a sample of a good sounding drum. The best drummers I know will end up with "ground zero" being about an inch in diameter... the mediocre drummer I know will have like a 2" "ground zero", the best drummer I ever recorded, his "ground zero" was literally no more than a 1/2" in diameter... I mean this brother was consistent, consistent, consistent... had feel for days and a tone anyone would look like a genius trying to record.
All sounds start at the source, and while we'd like to think that if we throw equipment at the problem we can magically fix the problem... that's bullshit. The equipment manufacturers will have you believe that you can indeed do alchemy if you use their widget over their competitor's widget, but the fact of the matter is that as recording engineers our job description is limited to taking variations of air pressure and storing them so they can be combined with other stored examples of other variations in air pressure later on. Nowhere in the engineers handbook does it say that we are ever supposed to turn water into wine.
Best of luck with all you do.
