I've been there many, many times and it's really a hard question to answer, depending upon if you're a photographer, comfortable below 150, etc., but here's my recommendations not in any particular order.
Fujikawa Maru, zeros in hold, lots of artifacts, loads of corals and life.
Shinkoku Maru..possible the best wreck dive for seeing everything in the lagoon. Impossible to really see everything n one dive. Best coral and marine life wreck.
Nippo Maru..shallowest of the deep wrecks, more pristine, tank on deck, great bridge.
San Fransisco Maru..deep but tanks on deck, mines, superb bow gun., totally loaded with bombs, torpedoes, etc. Definitely a deco dive.
Betty Bomber and Emily Flying boat...make sure you do them
on one dive..15 min on one, then move to the other for the rest of the dive. Both areat 60' or less. You just don't see planes like this anywhere else in the pacific.
You can also snorkel on a zero between dives. Ask to do this.
Fumitzuki destroyer...one of 2 warships in the lagoon, but this is much shallower 90-120. High speed props, bow gun, marine life. Very near the Shinkoku.
There's a lot more wrecks, but for the first time if you get these you've got the best quality ones in.
Yu can see videos of some of them here to give you an idea:
Truk Lagoon Videos and Diving
Have fun.