My favorite part of this hobby is crafting interesting combats for my players, however, I find D&D overly complex and slow moving.
I have enjoyed playing D&D 3.5 and 4, but am looking for something simpler. I am looking for a "rules light" game that does tactical combat well.
That's a bit of a tough request, usually the two are
usually seen as incompatible, and I'm not very clear on what you mean by handling tactical combat "well". The crux of the issue, I think, is how it is your group prefers to experience that tactical depth.
My first thought is for either Fate or Cortex+ a la MHRP. They do not come with a whole lotta pre-defined tactical rules, but during play the characters can use maneuvers on their turn to create advantages that can be used for bonuses (like
off-balance, sand in its eyes, or
in my sights). Both systems would let the GM define advantages within the battlefield before the scene play. Since those advantages are wide-open narratively, this can actually make combat a very detailed tactical experience
in the narrative realm. Unfortunately, since this all happens on a narrative/ToTM level and not at a rules/piece on the table level, many tactical-minded players will find dissatisfying. (But then you're asking for tactical & rules lite, so who knows...) Fate is genre-less by default, but MHRP is focused on Supers (i.e. you'd need to work out how to use Cortex+ in fantasy.) However, I know that a few other people have already run versions of MHRP in fantasy, and their work is available on the web somewhere. Both of these systems would favor players who are more creative at the table rather than those who are masters of a particular rules-set.
Now that I've mentioned Fate, I should mention Savage Worlds. It seems to be a law of ENWorld that any thread posing a "what system would be good for" question must include both of those as answers.
I don't have a whole heaping ton of experience with SW, but what I did have went fast. No, really, like so fast the group couldn't believe it. I wouldn't say that its particularly more tactical than some older/simpler editions of D&D (at least, it didn't feel very tactical), but dang it moves like the wind. I can't say that I thought there was a ton of room in SW for a lot of deep tactical thinking, more of a move and shoot feel. There's a relatively small number of basic tactical moves
here, and there's a plethora of "edges" for characters to take which can affect those, IIRC. However, if that's enough to trip your switches...
Most of the other systems I can think of don't really impress me as very rules light (and I'm not sure I'd call Savage Worlds that, either.) At least, I'm presuming you want some kind of tactical experience beyond Old-School D&D, but not as burdened with fiddly bits as 3e or 4e. I hope that helps.
