I wouldn't say that the UAD is better or worse than the Waves bundles, just different. I love the individual comps on the UAD card (1176 and LA2a revamps). However, I usually use thos on individual tracks during mixing or on something like a guitar bus. I also love the Pultec EQ on final mixes. But from waves, I like the L3 multimaximizer lightly on entire mixes and the linear EQ for narrower EQ cuts. Personally I like
the waves Audiotrack for individual EQ-Gate-light comping on channels inserts better than I like the UAD channel strip. Mostly because I really don't like the UAD channel strip compressor, and the fact that it doesn't offer a gate. For me, I would not want to mix in the box without either the Waves bundle or the UAD. I have found strengths in each that when used together really help me in my mixing.
As far as T-racks goes, it seems to be very muddy sounding to me. I NEVER use software to try and do the whole "tube" thing. If I want the tube sound, I get it going in, not coming out. Thats not to say that T-Racks is garbage or useless. Others may get good results with it. I can only say that every time I have tried T-Racks, other plugins (i.e. waves, UAD) sounded much better me and were much easier to use. However, those other things cost a lot more as well, so in reality they should work better.
I completely second the notion of getting better monitors first though. Great mixes can be done on the lowliest of gear with good engineers and musicians, but I fell positive that those same engineers and musicians would put out even better stuff had they been using better gear. The problem with home set-ups is mostly due to their lack of detail in my opinion. Any speaker system can be learned and utilized. You can learn that your spekers are light on the high end, heavy on the lowend and you can do a certain amount of mixing based on that. However, what you can't learn, or "fake" is the level of detail and imaging that may or may not be present with your speakers. Having studio monitors adds a degree of clarity and width that does not tend to reproduce well in the vast majority of home speaker systems. Using studio monitors allows you to hear those little details and allows you to really fine tune your mixing so that spacial placement, EQ'ing and level balancing takes on that whole third dimension.