What can I expect to hear from a decent analog FM Tuner?

Will these provide something warmer, different or enhanced from Streaming or CD?  I currently have a vintage Kenwood 700 M amp that I am using with Benchmark DAC2.
With FM you are at the mercy of the broadcaster. I listen every night to All Night Jazz on WUSF 89.7 Tampa. A good sounding station - but they use digital files. Not as good as the same music played back on my Marantz CD67. All the other commercial FM stations in my area broadcast musical dreck! So unless you have a college station nearby don't expect sonic delight from any analog tuner!
A good FM tuner with a good antenna can sound every bit as good as a digital source. How close are you to the broadcast towers? Are there stations you like nearby that broadcast with a good signal? What are your options for antenna placement (a good roof mounted antenna is optimal)?

As far as how it will sound, yes, it can sound different.  That depends a lot on the tuner you choose.

Here are some places to get more info about tuners and reception - fmtunerinfo and fmfool
I have six vintage FM tuners. Including two tube units (Fisher and Scott), plus a McIntosh MR77 and a Marantz Model 23.

I have a cabin in the mountains in Colorado. No internet so at the mercy of the airwaves. We have several great public and community stations in the NoCo area. Love listening to FM all day long via a tuner

At home have 2 McIntosh tube tuners but have recently switched to streaming ( especially WWOZ) via a macbook. Does it sound as good? it sounds digital, not quite as rich at the tuners but much easy to deal with and can listen to a wider variety including some hi res stations
It's kind of fun to stream radio stations over the internet, but the majority are streaming poor quality signals and will sound very "digital".  Radio Paradise sounds really good and some interfaces will let you sort by quality of the stream.

I listen to the jazz station in Seattle on my Magnum Dynalab Etude tuner while working.  It's about 50 miles away and sounds better than most internet stations, kind of "tubey", great detail, no static at all.
The main complaint I'd have on FM vs. streaming is that, on classical music, FM will compress the signal on the most dynamic parts.  Pop music is usually compressed to begin with, so it's not as big a problem with that genre.  But one nice thing about FM is, while you're at the mercy of the programming, some of it is quite good and may introduce you to really good music you might not otherwise hear or choose.
I have a McIntosh tuner in each of my 2 systems and listen to FM radio a lot and mostly because I am lazy. It works for me. 
FWIW, I have a couple of excellent vintage tuners and a local college. This AM I was listening to some classical music on my inexpensive Yamaha T-85. The audio was as good, or at least nearly as good, and either of my CDP's. Your main limitation on  FM radio is the quality of your station(s) and your preference for their program.  
I mostly listen to WWOZ (New Orleans community radio) over the airwaves. Many of the programmers play vinyl from the their own collections as well as cd's and the stations extensive digital files, and on occasion the station broadcasts live in studio performances. The signal is not overly compressed (unlike commercial radio) and can sound as involving to me as my other sources.

I really like the idea of broadcast radio, but as others have said it will only work for you if there are stations you want to listen to. In most urban areas there are public stations (i.e. NPR--mostly talk now,) community stations (often volunteer run and more enthusiastic than professional--which is all to the good in estimation,) and college stations (unfortunately too many have become NPR stations--I look for ones that are still student programmed.) Out in the sticks or in newer communities there are far fewer of these public resources and you are at the mercy of commercial radio which is generally not worth the effort. It is the programming that should drives the bus here--not searching for the ultimate audiophile experience.

Depending on distance and topography, you may well need a good antenna and a highly discriminating tuner to get a good signal--especially in stereo. In more favorable environments a simple dipole antenna can work fine. I favor vintage analog tuners and mostly use a McIntosh MR-78 although I also have a Pioneer TX-9500II that may sound better (and is a much better value--but not nearly as pretty,) and a Marantz 20B. Lesser vintage tuners are pretty easy to find and many still sound good so the cost of entry shouldn't be too high.
A good tuner even with just a ribbon antenna will pick up station great .Depending were you live .I'm on Long Island N.Y.