For reference, I have only ever built two gundams as a small child and struggled heavily with them. Now as an adult, I wanted to try my hand at building a kit and chose the RX-78-2 - the "grand-daddy" of gundams.
The kit was very easy and accessible to a gundam newbie like me - instructions are very clear and simple, while precision sticker application was minimal, and most parts were easy to take out of the frame and assemble. Almost like a LEGO set.