More robot game stuff: In a turn based fighting RPG with fighting robots, how would you like to level up your robot?

So, as some of you may have noticed my last two questions have been about robots, basically because I plan to make a robot based flash game.

Here are the last two questions if you are interested: #1 and #2

Anyway, the game I have in mind is a turn based fighting game. You have a robot and you need to win fights to progress in the game. You start off with a level 1 robot, and work your way up.

The question is, how would you like the level up system to work?

Here are some options I have in mind:

1— You start with a set and ready made robot, and need to win fights to earn credits. As you earn credits you can buy new and better weapons and armour for your robot.

(the weapons and armour have stats that make the robot stronger)

2— You start off with 10.000 credits , and need to buy 1 of 3 or 4 starter robots . As you win fights you earn more credits, these credits can be used to buy new and better robots, as well as buying new weapons and armour to add to your robot.

(new robots have better stats, weapons and armour boost stats too)

3— You start off with 10.000 credits, and need to buy: cables, steel, titanium, computer chips, and all kinds of other items to build your own unique robot. As you win fights you earn credits, you can spend credits on new robot parts, as well as weapons and armour.

(all items have stats and all affect your robot)

4— You start off with 10.000 credits, and you need to buy: computer chips, cables, titanium and other materials to build your own unique robot. As you win fights you earn more credits, these credits can be spent on new robot parts, as well as weapons and armour. As well as buying things, you will also earn experience. When you fight you will earn fighting experience, that will let you unlock special moves. As you buy and build, you earn design experience, allowing you to unlock discounts from shops and buffs when building.

(all items have stats, plus you may unlock features)

5— Other? combo?