I'd go with, I did read GRRM and Sandersons posts already so I may be a little skewed:

Aviendha (she can be in a link with Rand and still be of use in a fight and it's not like Rand's going to need a ton more OP, but the added power of a dual link will make whatever he does more potent and he will have the added bonus of a warrior woman who won't essentially be useless once she's in the link)

Mat and Perrin (bringing along the other 2 ta'veren, assuming it works in Westereos, would be a huge advantage. Even if it doesn't Matt and Perrin are strong enough fighters on their own to occupy any warriors Lannister has along)

Lan (even if he's not the absolute greatest blade master, he's the only one of the main cast that is accustomed to fighting alongside channelers, making him more valuable IMO than Galad or Gawyn etc...)

Nynaeve (keep her out of the link so she can run around to heal people and fight alongside Lan. This could backfire if the OP doesn't work since she'll basically be useless, but I think the odds are so far in Rands favor anyway that he can afford to take the risk) He could also consider Flinn in this role who would be slightly better if the OP wouldn't work.

Birgitte (let her pick off any women Lanister may have along from a distance so Rand doesn't get distracted or wind up letting Melisandre, Daenerys or Brienne get to him)

I would also give honorable mention to Be'lal and/or Sammael since they were both Blade Masters who could channel and obviously ruthless enough to not be bothered by slaughtering anyone in their way. Sure they may turn on Rand and kill him which is why I left them off my "final" list.