I Prefer Audio Technica:

http://www.sweetwater.com/store/detail/ATW3110-C/

 or Sennhieser:
http://www.sweetwater.com/store/detail/EW112G2-A/

I have had 4 each of these units (or earlier very similar models) for quite a few years now.  Programmable frequencies are not something to do without.   Between all the changes around DTV and additional rented mics, the ability to change frequencies is worth the extra cash.   More than a few times the ability to move a mic to another frequency has solved interference problems.

Also, these mics use AA batteries - half the cost of 9V batteries.

The AT mics have never failed.  I had one of the transmitter packs fail recently, and had to replace it.

The Sennhieser packs have been reliable, but the mic wires have been very fragile.  I recently bought new wire and rewired all of them.  I do not know if they have improved the wire they are using on new units.

I have never had an actor come to me with a Sennhieser pack with the batteries fallen out.  I put a small piece of gaffer's tape on the Audio Technicas battery door to prevent that.

I have resorted to gaffers tape to ensure the belt clips stay attached to both brands.

I provide sound for amateur, grade school & high school shows.

Hope this helps,
Dave

Stick with the major brands.  With some, the Lav mics are close to free.  You can then add headsets.  I with I'd known about these well-reviewed mics before we bought nine E6: http://www.microphonemadness.com/products/mmpsm.htm