Galvantula-
Pros-
- Solid 97/108 SpA. And Speed.
-Electric and Bug only gives it 2 weaknesses, albeit Fire and Rock.
- Gets Compound Eyes which makes using some moves more viable.
- Has solid Electric STAB in Thunder by TM, or Electro Ball via Level up. Also gets Signal Beam for STAB at Level 34.
Cons-
-70/60/60 Defenses aren't great, but enough to manage.
- You have no need for Compound Eyes until you get Thunder in Icirrus City. It can benefit, but not by much.
- Only Coverage moves are Energy Ball and Hidden Power.
Elektross-
Pros-
-115/105 Attack Stats allow for a mixed moveset.
- Has 0 Weaknesses.
- it gets via Level up are Thunderbolt, Thrash and Thunder Wave to compensate its low speed.
- Learns plenty of coverage moves by TM. These include Dragon Claw, Flamethrower, Brick Break, and Flash Cannon.
Cons-
-Has Base 50 Speed. This can be compensated with Thunder Wave, but nevertheless, it is still bad.
- The 3 Level Up moves in the Pros are the only good moves it gets via Level Up. This means a heavy reliance on TMs.
-Evolves rather late. Level 39 into Elektrik, and a Thunder Stone into Elektross.
Emolga- There is absolutely no reason to use Emolga over any of these 2. It has worse attacking stats than both, and worse Speed than Galvantula.
Just realized you said other. Blitzle is a viable option. Zebstrika has 100/116 Attack and Speed. However, it has a shallow Physical Movepool with Flame Charge, Wild Charge, Facade and possibly Rock Smash. You can use Zebstrika if you want, but I still prefer Elektross.
Conclusion - You can use either of the first 2. Both suffer the same cons from Level Up moveset. I prefer Elektross for a wider movepool and higher attack Stats. However, if you want higher Speed, use Galvantula.