I'll get behind several of the other people on here. If you liked Enterprise and Voyager (2 of the weaker Star Treks, but then any ST is good) and also like Battlestar, then you definitely need to check out Deep Space 9. It is by far my favorite of the Star Trek flavors (followed by original crew movies, then TNG). Like many of the series, the first season or two can be a little iffy until the writers find the groove with the characters. The first episode is a must see to set up the series and is good, but if you are on the fence during the first season just skip to the last episode of season 2 and pick up the Dominion arc that lasts the rest of the series. Seasons 3 through 6 are excellent. DS9 also has the largest battles of the franchise (sometimes even peaceful explorers have to fight). Give me Captain Sisko over Picard any day. Q visits the Enterprise and Picard plays Q's games. Q visits DS9 ...and Sisko punches him right in the mouth, lol.
Here's a little teaser trailer for you, clips from one of the more epic battles in Starfleet history backed with the epic song "Lux Aeterna" by Clint Mansell.
[video=youtube_share;MCm70favfYI]http://youtu.be/MCm70favfYI[/video]
Also, yes Firefly is great, but I guess not for everyone. Red dwarf is good and funny, and if you like it, Hyperdrive with Nick Frost as captain was OK. And yeah Leviathan, Stargate Universe was pretty good, well, it got good. The pilot was good and there were a few good episodes like "Time" in the first season, but by the time they canceled it, it had actually found its stride and got pretty good. Sci-fi shows almost always have hit or miss first seasons, then because they are really character-pieces, they come into their own in the 2nd season somewhere once the writers figure out how all the characters behave and interact. Networks either need to produce them for 3 seasons minimum or leave them alone. Every once and a while a series has a fantastic first season, but is the exception not the rule.