I would call Metroid Prime an action-adventure because the gameplay is oriented around exploration, combat, data collection, and problem solving. Most of the action in Metroid Prime is dedicated to shooting enemies, yes, but large sections of the game are dedicated to exploration and backtracking, problem solving, and reading logs.

The adventure elements in Metroid Prime are not tangential to the core gaming experience, as they are in Uncharted; instead, they are deeply and irrevocably tied to the game's foundation.

One is a Third person shooter, the other is an Action/adventure but here you go.  

Shooting  - Gears
Exploration -  Uncharted
Multiplayer - Gears
Coop - Gears
Story -Debatable
Animations -Uncharted

Theyre both good franchises (excluding Judgement and never played Golden Abyss)

PS, you would prob have a more fair comparison by asking for third party games due to many people hasnt actually played both and will choose the console they like.

Oh and Gears 3 is prob the best in the franchise.  Gears 1 has the most nostalgia though.

I personally prefer Uncharted (suits me more), but outside of preferences i wouldn't say neither is really "better". Gears is more consistent while UC has a larger range of quality. I'd say:

UC2 > UC3=GOW1-3 > UC1

They somewhat balance each other out in my mind.

Yea great advice on doing a third party game thanks.

Uncharted most definitely. The locales they choose for the game are amazing, the exploration, the witty humor, the action scenes, the puzzles, the acting, the graphics... it has the whole shebang. Personally, the gunplay doesn't bother me too much.

Very different types of 3rd person shooters. Personally I prefer Uncharted for many reasons, Gears never clicked with me.

Heh, how do you explore when you just have point A to point B style level design? ( In be for someone takes this serious)

I hate almost everything about Gears except the controls and shooting mechanics (only played the first). Uncharted (played all 4) has weak controls and shooting mechanics, but I really enjoy the story, characters, settings, over the top action, puzzles and HOT ladies.

I would say the combat in Gears is better, but at the same time, I feel no satisfaction killing in that games (save for chainsaw kills). Enemies are just bullet sponges who barely react to you filling them with lead. I hate that. In Uncharted, the enemy reacts to every bullet, and in a sort-realistic way. They get shot in the left shoulder, and they'll flail in that direction a bit. The gameplay for Uncharted is a lot more simplistic, but I enjoy it more. So it's hard to say which really has better gameplay overall. But if you factor in everything else (story, graphics, etc.), I say Uncharted is easily the superior series.

I think both series' excel at different things.

Gears has a huge advantage in co-op and online multiplayer, while Uncharted generally has the better single player experience.

Both are brilliant and I cant wait to play both on Gen 8 hardware.