Edited: 21/6/08
I've been playing this game for a while now, and I noticed everyone has their own way, as according to the forums and what I see online, they like to go early in a game for which cap ship to build first. Some like the Sova rush, others like a battleship to start, some prefer the Marza, and then others prefer the colonizer. After having seen and used them all, I'm throwing my opinion out there.
The colonizer is the best option for the first cap. People talk about how they only pick the colonizer, or only pick the battleship. Regardless, the colonizer is hands down the best one. There's a lot of things to consider:
1. If you don't get the colonizer, you have to buy a colony frigate, possibly two. People argue that the colonizing frigate is nice because once you've gobbled up your planets, you can then get neutral mines. Sure, that is a nice perk, but that takes forever. The colonizer's antimatter regenerates much slower, and loses 100 with each jump. Couple that with needing 90 to colonize and 1/2 antimatter point / sec regen rate, and it will inhibit your initial expansion. The colonizing capital ship regenerates 1-ish antimatter a second, and has a larget antimatter pool. Expansion is no longer inhibited by waiting to colonize.
The other drawback to using colonizing frigates is they eat precious minerals very early in the game. When you are only making 1 metal a sec and .5 crystal a sec, the 100-140 metal (race dependent) and 50 crystal that you have to give up for a colony frigate can really hurt early on, especially if you get two.
2. The colonizing cap has a special ability attached to it's colonize ability.
The Akkan (TEC) gives 1 free mine at lvl 2 and 2 mines at lvl 3. I don't consider this all that useful. I mean, it's a nice perk, but I'd rather have Ion bolt fully upgraded than get the small boost from getting those mines free and up and running quicker.
3. By expanding quickly with the colonizing cap ( as in getting your planets up and running quicker than you would if you were waiting for the colony frig), you are going to be able to afford a fleet a lot quicker. This is just common sense. You get more planets, you have more raw resources, your upgrading your planets quickly, and you have a much higher overall income rate. You economy is much more stable much quicker because you have more planets.
4. Sometimes, early game battles are decided by the accompanying fleet, not the cap itself. This doesn't apply after about 30 min, but initially fleets are so small (cap + 10-15 frigs) that the most effective thing to do is to micro target the opponents frigs, not cap (Well, unless you're vasari, see my post "Illuminator Spammer"). Since any cap can take hits from 10 - 15 ships for at least a while, it really doesn't matter that your cap is a little weaker than a battleship in the initial parts of the game.
I want to start bringing up the exception. TEC fleets just don't pack the punch I want in early games. This is the race I'm most likely to not pick the colonizer because the force of a Kol, Dunov, Marza, or even Sova can be much more useful.
5. This is the part that I use to convince myself to go colonizer. By expanding and getting an eco established early, you're going to make getting the second cap go much quicker. You can get a second cap if you so desperately need it, and by going with the colonizer early, the second cap will come much quicker.
I love the colonizer for every race. People say it's easy to destory. Not really. People say you can be rushed and pay by not having a strong cap. Bull. You can have a fleet to counter a rush if you really have to worry about that. Not to mention, each colonizer has some trump ability, and that includes the Akkan, that comes in very handy.
The evacuator becomes a seige engine in the end with lvl 6 and thanks to its nanite bomb no enemy cap is safe.
The mother ship not only has a beautiful colonizing ability, but malice and shield regen. It's lvl 6 is also nice if you do lose that one cap.
The Akkan has ion bolt, which is great for getting that fleeing cap. It's also great because if you fire it right as a mothership is firing shield regen, you cancel the ability and bring Advent fleets on par with TEC.
The % increase ability is ok, but Armistice is a beaut. You can stop a fight and escape with your entire fleet is you see you're going to lose. This may not seem that great, but say you have split your fleet, and he sends everything at the one that has armistice. That smaller fleet can run while your other terrorizes the enemy planets..
There's the case though...of smaller maps. These of course are different. On a map where you're almost certain you'll be engaging your opponent in less than 20 minutes, getting a different cap isn't a bad idea at all.
I'm not making an all encompasing statement here. Play Point Blank and choose the Colony Cap and you're writing your death warrant, but still, 95% of the time now I pick the colonizer. I only ever pick anything else on very small maps, such as Razor's edge, where having some ability such as a seige bonus will be necessary to win.
This is just my opinion. I welcome all criticism, positive or negative.