What level in the game are you?
Usually, you should sign the non-token one and use him appropriately. For example, if your team needs money, sell him. You can also keep the player as an extra player for training for bonuses, and then sell him later when required.
Signing the token one can be for different purposes.
(1) To sell for money as it provides more money as compared converting tokens directly into money (bank investment).
(2) To keep for use as a back-up player or a first team in the current season or as a player for the future. For the case where it is a player for the future, green packs will need to be spent to boost the quality of the player unless you play with a 3-4 star team every season. Some of the token academy players can be key or very good players though; for example, I got a DC that had the characteristics I was looking for in a DC except that it was a lower quality player than one you could get from the auction market. I signed the player, keep him as a backup DC, the DC earned a good rating in a match he played, but I sold him at the end of season via negotiations after my team played the important matches that were left to be played. It was mistake as my current 2 main DCs past their peak and had to be replaced soon. The next season (which is the current season), I had trouble finding DCs with the characteristics I wanted, and even though I bought 2 DCs, my team had weaknesses in defence, and still has now as the season is ending.
All that being said, usually signing a player (especially a scout player, a recommendation player or a token academy player - those that will cost you a lot of tokens) in very late the previous season for main use in the coming season is not a good option as the player will lose a star the coming season. Signing a scout or recommendation player might be even worst given that this will increase your teams chances of being put into harder competitions with respect to quality.