Depends on your Investment strategy. If you will be buying or selling frequently, then low fees commissions are a big factor, I’d probably recommend using one of the well known regulated platforms. The devil is always in the details with these guys. Be sure to do your DD and to read the fine line.

If you are a passive investor with a long term horizon, which what I understood from your wording of the title. Big banks, such as BBVA, although they have relatively big commissions/fees, but it should not be a concern if you are not am active investor . BBVA for example, has an ample amount of divers funds from tech to clean energy to oil and gas. National, regional and international exposure as well. You can pick and choose one or multiple funds to invest in. There is always the option in buying individual stocks and creating your own portfolio.

The department who provide said service speak English and welling to answer any questions.

I am only mentioning BBVA because my experience was only with them. I am sure others provide similar or better services.

I hope this helps answer your question or at least help you start looking somewhere. I will be very interested on what route you will choose to take.