Some personal favourites of mine:
E90-1
-The set I'm working on right now, not overly expensive and fairly interesting, the short prints are fascinating and each card in the set tells a story.
E92
-A personal favourite, lots of good looking backs to collect, and a great checklist, no extremely expensive cards either
Also, if you like too many sets, then maybe type collecting is for you (acquiring one card from each set). Great suggestions above aswell.
~Owen