I am not really what you would call a novice, but I am still learning and still ask LOTS of questions before a new machine purchase.... like right now I am in the market for a new machine so I have lots of questions out there.
I have the Ace250 w/9x12, Tesoro Silver uMax w/10x12 coil and a Fisher 1265X(recently sold and repurchased).
While I like the Ace250 for hunting coins in parks, church yards and such I really don't care for it in heavy trash. That might change as I am going to purchase a sniper coil for this unit in the near future. I understand that I will loose a bit of depth by doing so, but the target seperation is much better. I have found lots of good stuff with the Ace250, but if I had to have just one machine it wouldn't be the Ace250. That's not saying it isn't a great machine, because it is. It's just not a great all around machine for me in my area.
I love my Tesoro Silver uMax. With the 10x12 coil I can get some really good depth. One time I found an old large stove lid at approx. 2 foot with it. With that being said I wouldn't get excited about such an accomplishment. Most good targets are not going to be the size of a stove lid. In fact the smaller the target the more depth you loose, and that's with any machine I have played with. I really like the Silver for my area. I can hunt everything I want with this machine and get some great depth.
I haven't spent enough time with the Fisher 1265x to really give it an honest assessment. It is a good machine and will find lots of nice items. It is alot older though and is no longer in production.
As with any machine the more time you spend with it the more you learn, and that is what you have to do. Sure you can buy a machine that will notch out all of the unwanted stuff and pick up items within a few inches of the top of the soil, but you are going to miss ALOT of other stuff that is deeper. There is no way around digging junk and LOTS of it, that is unless you cherry pick the shallow stuff. Right now I am in the market for an upgrade from the Ace250. I want a machine that will get great depth, notching abilities, target ID, etc. I know that Target ID isn't everything and I know notching leads to missed targets. There are times that I do want to cherry pick sites for the shallow stuff, but I also want the extra power there too in case I want to do more. Can't use it if you don't have it, right?
If you have a dealer in your area visit them. Test a few different brands and models. If you live in a detector dealer free zone like I do then you have to just pick a machine. Learn the machine. ALL of the treasure seeking machines on the market will find the good stuff, but you have to learn what the machine is telling you. Even then you will still dig your fair share of trash.
Right now I am trying to learn how metal detectors function and how I can use different things to my advantage for what I want to achieve.
Good luck on your purchase.