Wedges, by far. In-ears are problematic if you do not have a very good engineer who works with you on a regular basis. They cut off other sources of sound, which means you need to have everything in the monitors which can be very confusing if the mix isn't perfect. With wedges, all you really need is enough to give you the cues you miss without them - usually a bit of kick drum and maybe some snare, bass, and some vocals - unless of course you are singing, in which case you don't want the bass as it will tend to make you sing flat, but you will want a bit of piano and/or guitar to get your pitch cues. What you absolutely do NOT want in wedges is a bit of everything - it will just get muddy and confused, and you will not be able to hear anything of value.
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