Welcome to the world of Gunplas.
Did you make any mistakes on your first kit?

You can progress to a MG kit once you are confident.

Err cutter shouldn't affect the nub marks unless you cut it really close (which you shouldn't). Knife on the other hand, is important.

RG is NOT recommended for newbies.. it has more intricate construction and much more parts.. some parts are more fragile and require special care.. i would advise u to try MG first to see how inner frames work, then move on to RGs

agree with hxiik on this one. RG is super difficult due to the higher number of smaller parts and also more fragile compare to normal kits . i myself still dont dare to open and star work on my RG kit also.

Definitely MG Jesta It's cheap, awesome looking, non-complex build, fully articulated hands (which for Jesta's weaponry, works sufficiently fine), and provision for LED

as stated above, MG Jesta is a good solid choice for someone starting out, it's fairly new and is solid enough to not contain too many fragile parts.. just be very careful of the hands
otherwise, you can try for MG RX-78 3.0 since that's like a 1/100 RG with the color separation and decals, so you can get a feel of the intricacy of RGs as well as how much more details can be put into a bigger kit
also MG MS-09RS Char's Rick Dom is a fun choice too, feel free to pick up whichever one you fancy as these would afford you quite a good experience.. just try to stay away from transformable units first.. those will give you a big headache if you're just starting out

also if you'd like, u can look into MG Gundam X.. i think that one is a fantastic build and i had a lot of fun building it

good choice, it make ur gunpla look better..

just to share my painted zaku2 ms-06s

the skill i apply for my gundam as well..
hahaha