Most CUs, even the larger ones, are very localized with few branches in one state or spread across a few states. The best CU for you comes down to what you are looking for. For many, the local CU can make most sense if it has good loan rates, no fee bank accounts, and the perks most people go to CUs for. CUs are less useful from a CC rewards perspective, though some CUs have good cards for specific types of spend (e.g. Pen Fed's 5% unlimited gas card). A few people also apply to CUs that are known for large CC CLs like NFCU and NASA (mixed posts on whether NASA still offers these). But even other CUs award large CLs. For example, Addison Avenue Federal Credit Union (now First Tech) issued me a 5k CL at 18 and it was up to 15k before I graduated college with zero income. While 15k is nothing special to me now, I can't imagine any major bank giving a no income college student a 15k CL.
What are you looking for with a CU? Easy access for auto loans and the type? A banking relationship with a CU you can go to and talk to someone in person? If so, a local CU with good rates makes sense as you can go to the branch and talk to them. Or are you looking for a CU with the best CC CL, in which case something like NFCU (if you qualify) or NASA might make sense. Or do you want a CU with a specific rewards card that optimizes your reward spend? Then Pen Fed can make sense.
For me, a CU's main purpose is as my primary bank for no fee banking and low rates for loans if I need them. I usually visit my CU before car shopping to get a specific rate to entice the dealership to beat those rates. I use my CU for most traditional banking functions because I don't get hit by surprise charges and fees. I even use my CU for 1 CC because of the low rates in the off chance I need to carry a balance for a month or two. I have rewards cards that optimize my spends and no CU rewards card I know of will improve my CC rewards optimization. The Pen Fed 5% Gas Visa card is technically better than my limited spend gas card, but I rarely go over my Sallie Mae's 5% gas spend limit. For me, a local CU makes most sense and an online CU makes less sense even though 99% of my banking is done automatically or online. For you, the answer might be different. You might even want to join 2 or more CUs based on your needs.
TLDR: What are you looking for from a CU? Recommending one is difficult without knowing what you expect.
