#1
i have this old guitar thats been past on from the family, made by my grandpop who was a luthier. It's about as old as my siblings who have used it til' the wood and the laquer kind of fell apart and stuff. Right now i'm given the choice by my parents (yup) to either repair it or get a new one. But i have a few questions before i do that:

-What guitar brands are obvious to avoid
-Which ones stay in tune real nice
-have slim/skinny enough necks for small amish hands
to stretch my fingers over
-no buzz fret (like zilch buzz fret)

I don't know if this is impossible, but i'm just a beginner with little knowledge of great guitar brands and i'd like to see what you pros can say about it. IF not, i'd like to know what guitars you guys prefer over others.
#2
Pretty much, a good rule of thumb with guitar is if you see a brand you're unsure of, search it on the used section of the guitar center website. But just starting out to play it safe look around local shops for names like, Fender (Squire), Ibanez, Gibson, Epiphone, Kramer, Jackson, Just really household names for guitars, and with tuning most guitars that are over about $200 (new) i've owned stay in tune quite well, but for much better tuning stability, get a guitar with a fixed bridge. And as far as the comfort level, the best way is to just play a guitar at your local shop and see if you like it, but if you dont have a local shop, the best best if your hands arent the biggest is Ibanez RG/GIOs. Slim necks that are easy to learn on. But your overall best bet is look around your local shop, and talk to the people that work there about you need, what you want to play, and your budget, they usually point you in the right direction.
#3
My opinion comes from my experience over the passed twenty something years playing guitar and owning a small variety of the brands out there at one time or another (Fender, Squire, Gibson, Epiphone, Ibanez, Washburn, Yamaha, Gretsch). Assuming that you are looking for an electric guitar I am going to recommend the ever so popular Epiphone Les Paul Standard. Reasonably priced, they feel like quality builds (nice and solid) with comfortable necks. They are quite versatile in regards to sound overall, and can easily reproduce that iconic rock guitar sound (thick and beefy). I find the single cut Les Paul body comfortable as well. I could go on and on as a "Les Paul" guy but I'll spare you and stop myself right there.

As LiquidOcelot7 has mentioned, it is best to go out and visit your local music retailer(s) and test out a variety of guitars to discover what you like and don't like. I do not have anything to add as far as what brands to avoid. But on the subject of guitars that can hold a tune, once again I have to recommend the Epiphone Les Paul Standard. The Epi LP Standard that I used to have stayed in tune far better than the Gibson SG I had, and much better than my Gretsch G5120 Electromatic hollow body. The majority of Epiphones come with Grover tuners. Good luck and have fun with your search!
1984 Yamaha SG1000X
2006 Epiphone Les Paul Black Beauty 3
2011 Fender Mustang IV
2011 Gretsch G5120 Electromatic
2014 Fender Mustang I (V.2)
2016 Gibson Custom Shop Standard Historic 1957 Les Paul Goldtop Reissue VOS