A good reference for etf vs mutual fund: https://www.bogleheads.org/wiki/ETFs_vs_mutual_funds

My advice is start with a four fund Vanguard portfolio based on your age (use their target date retirement funds as a guideline, e.g. VFFVX). Probably don't want the target date fund in your brokerage for a few reasons, so buy the individual funds and rebalance yearly. Start with mutual funds because they can convert to ETFs, but not the other direction. And because they're easier to buy and sell, no bid ask spread.

If it's for your siblings, hard to say whether you should max out your retirement funds (401k, IRA, Roth) this year or leave it in the brokerage. Retirement funds can be pulled from via SEEP but it's very inflexible. The way the trust is written, possibly just leave it in a brokerage for now. Careful as a trust has legal implications. Might want a lawyer and CFP to review your case.

Have had ally for 5+ years. Reason was it is the best paying bank that also passed the Dodd Frank stress test the year I signed up, e.g. it's a pretty safe bank as they go. Most banks paying more are thus not very safe with investments and probably would be less likely to weather a huge financial downturn. Or their great rate is introductory and will change.

Recently I had to do a couple of customer service calls and waited for 3-4+ hours every time. Still highly recommend them. Have never needed in person banking services and their self service website and app is great. But I cancelled my Bank of America account after waiting in person over an hour one time. So basically all banks occasionally have crappy customer service. Ally just actually pays you in return.