25+ time horizon currently about 15k in assets what are my options that have the best growth opportunity
Brokerage account gives you the most options. For "growth opportunity", you'll have to pick the assets.
Assets will perform differently (including crash) at different times. The US stock market probably comes the closest to "25 years of growth", but I wouldn't be in a hurry right now to be committing your capital. Wait until the markets smash, then buy on the cheap.
I have MJ and SPY in my relatively small IRA but for the bulk of my retirement (employer sponsored 401k) I use an automatic allocation feature of "Ultra Aggressive" which spreads out the capital among various low cost stock mutual funds.
Yeah...it has moved almost 50% in 14 trading sessions. Looks like it is going to make a run for the previous high at 40. One option would be to buy when price closes above the high made at the beginning of the year or wait until it pulls back some.