I seem to be one of the only collectors on here who really do like the UFT line of Trash Pack. I have a complete series 1 and a near complete Glow Mania set. The figures are just awesome and as a collector I have never had any problems with them in any way. They feature some of the funniest sculpts and the weapons they hold just add to the comedic factor!
I don't play with my Trash Pack or UFT figures, so I don't know if this is where the flaw may lie. Don't get me wrong, I have loaded them in the spinner and made a few of them "fight" in the arena with excellent results. May I ask what were the flaws that you have observed or read about the UFT?
There really isn't a truly "rare" figure; however, you must buy certain play sets as Strontium Dog mentioned to complete your entire set. Specifically, you must buy the areas for the master trash and 12 figures only come individually with the spinners/launchers. I have found (especially for Glow Mania) that if you pay attention to the figures displayed on the outside of the 12 packs, you can very easily collect the entire set of "commons". I picked up 6 12-packs for GM and have all the commons with no doubles! Very excited about that!
Personally, I feel these series are WAY too good to pass up!