Hello ameracole.
First of all, congratulations. Not many people have a few offers to chose form, and now that you have a few offers especially with the bigger service companies- AWESOME ! Congratulations!
I'll answer your question in parts. First of all the big AWESOME -because big companies provide some great training, which goes a long way in your career, and just makes you a better technical person, not to mention the HUGE value addition to your resume. People may argue about small companies and big companies beign the same, but I strongly deny that and have seen it first hand. A recruiter at the OTC in Houston earlier this year asked me to leave my "then service comapny" and join the big red, or the big blue or other bigger service companies to stand a chance to make it to conoco.

Yes, on my face- a 55 soemthign yeaar old lady who recruits geoscience professionals

And guess what, in 5 months from then I got into another major oil company. But the fact is it helps to have a big name on yoru resume, and yes, you do get better training companed to smaller companies where you are just working all the time-but you do learn stuff in both cases. Now, with regards to the "wanting to work in an E&P later on"- that is just a matter of time. With solid service company experience E&P's will grab you- no matter what- if you try and if you deserve it/ convince them int he interview ofcourse(being blunt here). I got a bachelors in chemical engineering, masters in Petroleum Engineering, worked as a hydraulic fracturing field engineer for 3 years, and now am with an oil major - E&P. So, hopefully I'm eligible to throw my 2 cents towards this thread. Pretty much exactly the path you may want to take down the road !
Without teasing you any further, and with no more philosophy I shall tell you what I'd do if I were in your place few years ago with the choices you have, knowing and having seen what I have seen in the past few years. Here goes:
I would chose Production Enhancement aka (fracing and acidizing) - which I think is with the big red from what decipher from your post. I would refrain from cased hole wireline due to several reasons. As a Reservoir Enigneer in my company I don't deal a "WHOLE LOT" with logging and logs- ofcourse I do, but the petrophysicists play with it all the time. Besides it will be way more moving around compared to a frac crew, as most fracs these days are multipad laterals and you'd be on a location for days/weeks(exceptions exist ofcourse, but this is from a convenience perspective). Having said that, doing cased hole wireline for years and having no exposure to stimulation (production enhancement/ frac'ing, acidizing, mini frac's etc etc.) may not be the best idea considering what youw ant to do. A friend of mine with baker mentioned to me that you get into loggina dn youc ant move for 4 - 5 years once ur in logging, after which they consider you for a DD. That is a really logn time doing M/LWD with not as much variety as being on a frac crew- where you see gel, slickwater, hybrid jobs, DFIT analysis, microseismic crews at work, tracer comapnies, and a multitude of third party companies workign around you.
Besides with Production Enhancement and you wanting to be a production engineer in the future, you will handle a lot of re-fracs etc if you;d join an oil company (that is how it works in my company- production engineers handle the refracs and the completion engineers handle the main frac jobs), . Also you will see and work with several E&P companies in several scenarios, and perform a variety of jobs which will value add to your resume and improve your skill set so much that you can easily become a completions or production engineer with an operator, and most important of all- you will be a value addition to their team and an asset who can really contribute because of your experience.
Overall, though people may not agree I think in logging you become an expert with a few tools which is specific to that company, but with frac'ing there are no tools to master- yes there are fluid systems, but the dynamic nature of job is a fun experience and will help you more I think.
I hope this helps,a nd I'm glad I could throw in my 2 cents. Good luck to you whatever you chose to you !
Cheers !
Oilngasninja