We can't answer this for you. It's about your goals and other things that pertain to you as an individual. If they are both reputable and decent agents then think about what you want your agent to be.
There are pros and cons to a large agency and a small one.
Pros to large agency is that they most likely have connections to the best publishers and have a chance at getting you a good deal. Cons to a large agency is a large agent with a bunch of clients (especially rock star ones) might not give you much personal attention. These agents tend to be harder to get in touch with when you need them and they might not be as communicative as you might want. In other words, these agents rarely hold your hands. They tend to give their biggest authors the most attention because they are the ones bringing in the money and if your work doesn't sell you might have a short lifespan with a rockstar agent. Those are things to think about.
For a smaller, new agent, make sure they've sold something and have contacts first before signing. Pros to smaller agents are more personal attention. They tend to be closer to their authors and more hands on meaning they will be more helpful with edits and getting revisions and rewrites done. They tend to be better communicators than the bigger agents. For example, a smaller agent with a few clients might get back to you the same day opposed to a bigger agent you might have to wait a week or weeks to hear from. Some big agents are so busy that you might have to schedule a conference call or chat before being able to get a hold of them. They also might give your work more time to sell versus giving up on you within months. Cons to smaller agents is they might not have enough experience, might not have enough contacts which means a harder road to selling your work. Do you want your hand held and someone to walk you through the process and give you that extra push? Smaller agents tend to fit these individuals better.
I don't want to generalize, but in my experience, this has been what I've seen. But, every agent is different so you can't know until you get a feel of their personality but you should stay away from agents who don't communicate well. Even if they are supposed to be great, that's a bad sign. There have been many writers right here on AW who signed with rock star agents then a year or so later wanted out of the deal because their agent paid them zero attention or kept putting their needs on the backburner.
You can find a good agent where you can feel like more than just a number. You want an agent who isn't gonna stick you on the bottom tier as if you aren't important. Whoever you sign with, they need to be just as invested in your work as you are.
Me, I'd prefer a smaller agent who I feel will work harder for me and who I can contact whenever need be. They of course will have to be established and have sold books like the ones I write but yes, a smaller agency would be my first choice.
Note, I am not looking. I left the trade world years ago. But, when I searched, this is what I wanted. I wanted an agent I could rely on and not someone who puts their clients in groups consisting of who is important and who isn't. Agents are just like pubs. Some tend to not treat all clients the same. The moneymakers get the star treatment. I'd prefer an agent who treats all his or her clients as important despite what level they are in their careers.
Good luck!