The higher ones in the list (apart from the Mk1) are better value for money, so buy the most expensive one you can afford.
The Mk1 rifle has a niche advantage in burst fire but otherwise is inferior to the slightly cheaper Marsec Autogun.
Lasers in general seem to be a waste of time with the exception of the L50 as the el cheapo "Saturday night special". Though arguably a good melee weapon would be better in most situations.
The two sniper weapons are difficult to use for reasons I will go into elsewhere but there is no point taking the laser version apart from very special circumstances.
So overall explosive weapons and grenades seem to be the go-to ranged attacks just because of the much higher probability of an effective hit, plus the tactical utility of reshaping the terrain (on most maps).
But these are relatively expensive so you must "cut your cloth".
Armour seems poor value because it's never going to give you more than a chance to survive a hit, and once that unit is dead the benefit is lost and can't be transferred to another unit (like all other weapons and items can).
Basically you got the right assessment of the weapons. Las rifles have an advantage over all other guns over distance...they punch 100% damage without losing any & highly accurate. MK1 is handy, can shoot it like a pistol almost, cheap AP's, accuracy is reasonable...Best for close to medium range. A group of Sniper rifles is a very effective against most situations, a sniper single unit with good stats can repeatedly perform surgical actions. You're right about explosive weapons and opponents using them. But the big guns & launchers soon run out of ammo with one exception the Auto Blaster. The best gun in the game. Will kill most armoured men, make handy holes in walls, good accuracy...expensive but used wisely gives an edge. The problem with weapon comparisons is context. Each mission is different,varying opponents and their ever changing choices and the unique unfolding of the individual battle. Even when the ingredients are the same the outcome can be wildy different. It also comes down to personal style and likings as much as strategy & tactics. Rabid is bang man, rocket launcher expert. If he can take you out early...he will but on quite a few painful occasions he's saved a few rockets late in the game and reversed his situation and won. I used to win Underground using a lot of smokes. Then people caught on and then it became a disadvantage. It's still useful to have smokes but I use other complimentary weapons for different effects.
I actually thought the SP50 WAS a pistol until I checked the stats more carefully - it?s a huge beast the size of an autocannon. Crap but cheap - is it supposed to represent some earlier generation of laser weapons or something?
I purposely create 50% games for us to use the lesser credit weapons, changes the dynamic of the missions. As I often do with 150%/200% to use the more powerful ones. With this facility game creation is compelling.
Xeno's low & high cost games are great...make some more dude. 400% credits, no walls left...low credits it's all power swords, knives growling and punching each other...yes punching can kill!