In my opinion, Voyager's greatest (?!) contribution was in poorly written stories that took Star Trek far enough off the rails that no more really good Trek could be made without a semi-reboot of the franchise. Which resulted in the excellent movie earlier this year.
So, um, right on, Voyager! Yeah....
I did kinda like the Voth, Species 8472 (before the writers immediately turned around and neutered them), the concept of the EMH, and the design of the Delta Flyer.
true, voyager is the culmination, and completion of star trek. four franchises about exploration, one about politics and war that felt a lot like stargate. three of the exploration storylines with the always same aliens and adversaries, klingons, romulans, etc, and about the expansion of the federation. voyagers story arch was the most ambitious, the aliens truly alien, and it's crew the best. after the completion, the prequel just couldn't work, so they had a go with a star trek parody, star trek 11.