MG Blitz Gundam
Brief story time: my first articulated "model kit" was the G-Frame Blitz Gundam. I was amazed at the simplicity and aesthetic for <10 USD, and it inspired me to get into the hobby.
Late last year I got the MG Blitz Gundam, and it is everything I liked about the G-Frame times 20.
To add on to this, as long as you don't make any physical changes like etching new lines or drilling new holes, you can always walk anything you do back. Obviously if you do a full paint job that might take a while strip off, but it's still fully reversible. So build it, and then as you get more practice you can come back and do your additions.