You didn't say much about what she will be using it for., so I'll assume she is the average plain Jane
In my country,since it was introduced in 1998, the Fazer (now FZ6)) has been considered both the beginners bike and "women's bike" of choice - above any other. It has more or less been so for quarter of a century (which means many great used deals to be found).
It's popularity has come about for good reason - as it is an awesome allrounder for tarmac, it is well matched for the types of roads we have arround here, and ergonomically it will suit many body types. It is affordable. It is well suited for beginners and advanced riders alike. It looks good.
It is a great tourer with fairly straight up sitting position. It will keep pace with sport bikes in the twisties, but can also handle some gravel. The engine is smooth and likes to rev. It has enough power to not be too fuzzy all the time about which gear you are in. It is cheaper than the V Strom. Most should be able to plant their feet. But it is not an offroader!!!
The FZ6 will handle gravel roads just fine - even fairly beat up ones. But, you won't be standing up on it (maybe lift your bum over a bump) or ride even remotely agressively.
But, 10/90 gravel/tarmac, and especially for a beginner without off road ambition - it may be the perfect bike? If she has offroad ambitions for the not so distant future, then she will want something entirely different.
What is more important to most beginners riders than CC is the smoothness of power delivery through whatever ammount of power we are talking about. The second is not so much weight as it is how easy the bike is to man-handle from the saddle - irrespectively of wet weight. Many low displacement adventure bikes are tall and top heavy, with a smoothness in power delivery that rivals a cangaroo on speed.
If she has ambitions to ride beyond the smooth tarmac and gravel within a couple of years, then she should go for the "cangaroo". If she plans on sticking to paved roads - then she should go for a more road oriented bike.
By comparison, the 390 adventure (awesome beginners bike for a person with some offroad ambitions), is quite unforgiving in it's power delivery (racy). Whereas the Fazer doesn't much seem to care what gear you are in or what revs you hold, the high compressed and weaker and racier KTM is very finicky.
The low seat of the Fazer instills far more confidence when it comes to man handling the bike than the 390 Adventure does (or any dual sport or adventure bike). In my opinion, the Fazer are among the top 10% best bike options for 90% of the beginners out there. Most beginners think they know what they will want or need as they improve, but most don't. If you yourself are an adventure rider and plan for her to partake in your thing, a more specialized bike might be in order? However, if she is to find her own way, - then the better starting point might be something more conservative? Like an old Fazer with ABS?
If she has offroading ambitions, I would consider the Honda CRF 300 rally or the KTM 390 Adventure, or the HONDA CBX 500. The CRF is more expensive and less of a hoot on the tarmac than the KTM. The KTM makes for better touring, and is still great in the rough (albeit not as great in the rough as the CRF). The KTM is the cheapest.. The CBX is the better tourer, but is still quite capable offroad, though not as good in the rough as the other two. The CBX is also the most expensive. All three bikes are however very good both on road and offroad. But, if you are short - you need to man up and practice, Also the second hand market is miniscule compared to the Fazer. Best value deals to be found on the fazer.
You will hear a lot of tout for 250-300cc bikes, and other low weight dual sports and adventure bikes. In this forum, I will agree most if the time - riding solo RTW, it usually makes sense. But, most beginners will start out "touring" on tarmac (with the occasional stretch of mostly good quality gravel), long before they even attempt any "adventure motorcycling".
For touring - engine power really matters a lot more than the small displacement riders want to admit. If you want to keep up with your friends, going up some twisties to a mountain top, passing the occasional car - you surely will fall behind most. More importantly, the noob may very well still try to keep up, and due to lack of acceleration, will try to retain speed where he shouldn't - ending really bad.
So going from offroad oriented to street oriented
- Honda CRF 300 Rally
- KTM 390 Adventure
- Honda CBX 500
- Yamaha fz6 (Fazer)*
*The Fazer is discontinued, but also very cheap.