Based on who got through to Judge's Houses and based on JH performances:
Boys
Matt Terry
Christian Burrows
Freddy Parker
Girls
Gifty Louise (she is getting better with performances)
Caitlyn Vanbeck
Emily Middlemas
Overs
Ivy Grace Paredes (she applied for wrong type of visa, got necessary visa but was too late - sorry but a filming location shouldn't stop you from continuing in a British singing competition. Arguably best singer this series, and a ballad singer might be just what the lives need considering who made it to lives)
Janet Grogan (has a distinctive voice and one of the best performers imo in JH)
Saara Aalto (though with her it's all about song choice)
If Ivy couldn't come back then I'd say Christopher Peyton - though he already has a career in music so I might argue he doesn't need X Factor.
Groups
Four of Diamonds
5AM
The Brooks (Brooks Way is a terrible name and may hamper their chances)