Sexy Letitia is great company and makes sure her clients leave smiling. The other lady, I've never seen so can't comment.
I guess it all depends what you are looking for in terms of looks, services offered, personality etc as one man's idea of fun is someone else's torture. The only suggestion I can really give is to take a look at profiles until you see something that takes your fancy then cross-reference it with UKP to see if real clients agreed or if the AW profile is all bullshit to sucker you in and then take a deep breath, pick someone and go for it.
Choice around Reading isn't great right now so you could also put up a reverse booking and see who bids on it. Just be aware that some women bid on anything whether they provide what you are looking for or not so make it clear when finalising arrange,nets if there is anything you specifically want included in the session.
Good luck and don't forget to come back and write a review once you've taken the plunge.