Both Coinomi and Trust Wallet are non-custodial clients, so you will have access to your seed and/or private keys with either one of them. There is no difference between them on that front. Both are closed-source, so you aren't getting any benefit from one over the other there either. What makes them different is coin support. One wallet might support an asset that the other one doesn't. I am not sure how either one of those work in terms of fees, and do you have the freedom to select how much you want to spend on transaction fees or not.