Question:
Hermes Bel Ami
and Terre d' Hermes
and welcome back!

Answer:
I will say the following can compete any niche in my book,
Antaeus
Kouros
Zino
Santos
Gucci PH
Aramis 900
Dior Homme

Answer:
I think there are many many excellent designer fragrances. My absolute favorites are:
R de Capucci. The best fresh chypre I ever smelled. All seasons
Cacharel ph. The most beautiful use of a nutmeg note ever. Autumnal-Decembral.
Adolfo Dominguez Vetiver hombre. Light-hearted yet sophisticated. My favorite barbershop scent. Best for Spring&Summer, but I wear it anytime
Valentino Vendetta pour homme. I do not know of a better incense smell. Beats every CdG I've tried. More autumn-wintery.
Monsieur Balmain. The best designer citrus IMO. Gorgeous lemon. Endorsed by Luca Turin as the sunniest fragrance ever
Richard James EdT - One of the finest masuline florals in the designer world. Tuberose and suede notes, very sophisticated and British gentleman-like
René Lezard - Identité pour homme. While this German design house produces crappy perfumes in general, they hit the jackpot on this one. Lutens excepted, my favorite gourmand- because it's restrained and elegant.
All of these are unconditional five-star favorites of mine and no niche has anything on them IMO.
I would add Patou ph, Jil Sander Man Pure and a few others, but they are more expensive and harder to find than most niches. The above are anywhere from affordable to dirt cheap.

Answer:
If you like earthier things try No19, I know it's a 'feminine' fragrance but I think it really suits men and could be to your taste?
My favourites include;
Kingdom
No19
Dior Homme
Mugler Cologne
Gaultier2
Lolita Lempicka Au Masculin
Peony Angel
Shalimar
I can't think of any more right this very second.

Answer:
M7
Versus Uomo
Vetiver - Guerlain
Feeling Man - JS

Answer:
Burberry London is by far the best I've experienced.
Bvlgari Black is very good and I also really enjoy Aqua Bvlgari
Gucci Envy is nice

Answer:
If we consider CdG a non-niche house, then I recommend Seguoia, Avignon and Zagorsk.
And also:
Chanel´s Egoiste
Guerlain´s Shalimar, Mitsouko and Jicky
Lalique pour Homme (the Lion)
YSL Nu edp
cheers!

Answer:
YSL M7
Gucci PH
Guerlain Vetiver
Guerlain Heritage
Chanel Egoiste
Chanel Antaeus

Answer:
I love so many. Here are some that I would mention:
Alexander McQueen KINGDOM
Burberry BRIT, LONDON, TOUCH
Bvlgari AQVA, BLACK, PH
Cacharel NEMO, PH
Cartier DECLARATION, MUST
Chanel ANTAEUS, EGOISTE, PLATINUM
Christian Dior FAHRENHEIT, HOMME
Dolce & Gabbana BY, PH
Fendi THEOREMA
Givenchy XERYUS, XERYUS ROUGE
Gucci ENVY, PH
Guerlain L’INSTANT PH
Hanae Mori EDT
Helmut Lang CUIRON
Hermes BEL AMI, TERRE D’HERMES
Issey Miyake L’EAU D’ISSEY
Jean-Paul Gaultier LE MALE
Laura Biagiotti ROMA
Loewe SOLO
Lolita Lempicka AU MASCULIN
Rochas MAN, POUR LUI
Salvatore Ferragamo
Shiseido BASALA
Everything by Mugler
Ungaro III
Everything by Van Cleef & Arpels
Versace DREAMER
Yohji Yamamoto YOHJI HOMME
Everything by YSL

Answer:
For me Eau d'Hermes, Gucci pour Homme, Parfums de Nicolaï New York (which is perhaps almost a niche but can be gotten pretty cheaply) and YSL Rive Gauche pour Homme might be the tops. They all feel very distinct and powerfully themselves to me. Polo Double Black (too new to be really cheap yet but it'll get there) also smells heavenly some days.